Use TX end IRQ instead of busy wait

[openparking.git] / firmware / modbus.c

diff --git a/firmware/modbus.c b/firmware/modbus.c
old mode 100755 (executable)
new mode 100644 (file)
index a49bd87..2b2a255
--- a/firmware/modbus.c
+++ b/firmware/modbus.c
@@ -11,6 +11,7 @@
 #include <util/atomic.h>
 #include <util/delay.h>
 
+#include "clock.h"
 #include "modbus.h"
 
 #define BUFSIZE 128    // must be a power of two
@@ -42,15 +43,12 @@ static uint8_t mb_unit_id;
 
 #define UART_BAUD      9600
 #define UBRR_VAL        ((F_CPU + 8UL * UART_BAUD) / (16UL*UART_BAUD) - 1)
-#define wait_one_byte()        _delay_us(10*1000000/UART_BAUD)
 
-#define get_clock()    (TCNT1)
-#define CLOCK_SPEED    (F_CPU/1024)
 /*
  * According to Wikipedia, it is indeed 28 bits = 3.5 bytes without
  * start- and stopbits.
  */
-#define TIMEOUT                (28*CLOCK_SPEED/UART_BAUD)
+#define REQ_TIMEOUT            (28*CLOCK_HZ/UART_BAUD)
 
 uint16_t hold_regs[MB_N_HOLD_REGS];
 
@@ -196,7 +194,7 @@ void modbus_poll()
                if (rx_bytes == 0) // nothing received yet
                        return;
 
-               if (get_clock() - last_rx < TIMEOUT) // still receiving
+               if (get_clock() - last_rx < REQ_TIMEOUT) // still receiving
                        return;
 
                if (rx_bytes < 4) { // too short
@@ -268,14 +266,19 @@ ISR(USART_RX_vect)
        }
 }
 
+ISR(USART_TX_vect)
+{
+       UCSR0B &= ~_BV(TXCIE0); // disable further IRQs
+       ctl_pin_off();
+}
+
 ISR(USART_UDRE_vect)
 {
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
                if (tx_head == tx_tail) {
+                       UCSR0B |= _BV(TXCIE0); // enable xmit complete irq
                        UCSR0B &= ~_BV(UDRIE0);
                        tx_tail = tx_head = 0;
-                       wait_one_byte(); // FIXME: too long busy-wait
-                       ctl_pin_off();
                } else {
                        UDR0 = txbuf[tx_tail];
                        tx_tail = bufptr_inc(tx_tail);